Topics in the November 2008 Exam Paper for CHEM1102

Click on the links for resources on each topic.

2008-N-2: Periodic Trends in Aqueous OxideCrystal Structures

2008-N-3: Solubility EquilibriumHydrolysis of Metal IonsCoordination Chemistry

2008-N-4: Hydrolysis of Metal IonsCoordination Chemistry

2008-N-5: Weak Acids and BasesCalculations Involving pKa

2008-N-6: Physical States and Phase DiagramsIntermolecular Forces and Phase Behaviour

2008-N-7: Physical States and Phase DiagramsIntermolecular Forces and Phase Behaviour

2008-N-8: Kinetics

2008-N-9: KineticsKinetics - Influences

2008-N-10: Representations of Molecular StructureCarboxylic Acids and Derivatives

2008-N-11: Stereochemistry

2008-N-12: AlkenesStereochemistry

2008-N-13: AlkenesAromatic Compounds

November 2008

2008-N-14: Structural Determination

2008-N-15: Synthetic Strategies

November 2008

22/08(a) The University of Sydney

CHEMISTRY 1B - CHEM1102

SECOND SEMESTER EXAMINATION CONFIDENTIAL NOVEMBER 2008 TIME ALLOWED: THREE HOURS

GIVE THE FOLLOWING INFORMATION IN BLOCK LETTERS

FAMILY NAME

SID NUMBER

OTHER NAMES

TABLE NUMBER

INSTRUCTIONS TO CANDIDATES

• All questions are to be attempted. There are 22 pages of examinable material.

• Complete the written section of the

examination paper in INK. • Read each question carefully. Report the

appropriate answer and show all relevant working in the space provided.

• The total score for this paper is 100. The possible score per page is shown in the adjacent tables.

• Each new question of the short answer section begins with a •.

• Electronic calculators, including programmable calculators, may be used. Students are warned, however, that credit may not be given, even for a correct answer, where there is insufficient evidence of the working required to obtain the solution.

• Numerical values required for any question,

standard electrode reduction potentials, a Periodic Table and some useful formulas may be found on the separate data sheet.

• Page 24 is for rough working only.

OFFICIAL USE ONLY

Multiple choice section Marks

Pages Max Gained

2-10 30

Short answer section Marks

Page Max Gained Marker

10 5

11 7

12 8

13 5

14 3

15 3

16 2

17 4

18 5

19 8

20 5

21 5

22 5

23 5

Total 70

CHEM1102 2008-N-2 22/08(a)

• Briefly explain how the concept of electronegativity can rationalise the existence of acidic, basic and amphoteric oxides.

Marks3

Draw the face-centred cubic unit cell. 2

CHEM1102 2008-N-3 22/08(a)

A solution is prepared that is 0.10 M in potassium bromide and 0.10 M in potassium chromate. A concentrated aqueous solution of silver nitrate is added with stirring. What is the concentration of Ag+(aq) ions when silver bromide first appears? Ksp of AgBr = 5.0 × 10–13

Marks 4

Answer:

What is the concentration of Ag+(aq) ions when silver chromate first appears? Ksp of Ag2CrO4 = 2.6 × 10–12

Answer:

What is the concentration of Br–(aq) ions when silver chromate first appears?

Answer:

• Calculate the equilibrium constant for the following reaction.

AgI(s) + 2CN–(aq) [Ag(CN)2]–(aq) + I–(aq)

Data: Kstab of [Ag(CN)2]– = 3 × 1020; Ksp of AgI = 8.3 × 10–17

3

Answer:

CHEM1102 2008-N-4 22/08(a)

• Which of the cations, [Fe(OH2)6]3+ and [Fe(OH2)6]2+, has the larger pKa? Briefly explain why.

Marks 2

• Consider the compound [CrCl(OH2)4(NCS)]Cl⋅2H2O. 3

What is the oxidation state of the transition metal ion?

What is the coordination number of the transition metal ion?

How many d-electrons in the transition metal ion?

List all the ligand donor atoms.

• Consider the complexes cis-[PtCl2(NH3)2] and trans-[PtCl2(NH3)2]. Draw the structures of the two isomers, clearly illustrating the stereochemistry.

3

Briefly suggest why cis-[PtCl2(NH3)2] is an effective anti-cancer drug, but trans-[PtCl2(NH3)2] is not.

CHEM1102 2008-N-5 22/08(a)

• Buffers made of mixtures of H2PO4– and HPO4

2– are used to control the pH of soft drinks. What is the pH of a 350 mL drink containing 6.0 g of NaH2PO4 and 4.0 g of Na2HPO4?

For phosphoric acid, H3PO4, pKa1 = 2.15, pKa2 = 7.20 and pKa3 = 12.38.

Marks5

Briefly describe how this buffer system functions. Use equations where appropriate.

Is this buffer better able to resist changes in pH following the addition of acid or of base? Explain your answer.

CHEM1102 2008-N-6 22/08(a)

• The figure below illustrates the phase diagram for water. The points on the diagram correspond to:

A: Triple point (0.0098 °C, 0.610 kPa)

B: Normal melting point (0 °C, 1.01 × 102 kPa)

C: Normal boiling point (100 °C, 1.01 × 102 kPa)

D: Critical point (374.4 °C, 2.18 × 104 kPa)

Describe all of the phase changes that occur when water at 1.01 × 102 kPa is slowly warmed from –20 °C to 200 °C.

Marks 3

Describe all of the phase changes that occur when water at 0 °C is slowly compressed from 0.500 kPa to 1000 kPa.

gas

B

solid

C

D

liquid

A

Temperature (not to scale)

Pres

sure

(not

to sc

ale)

THIS QUESTION CONTINUES ON THE NEXT PAGE

CHEM1102 2008-N-7 22/08(a)

Addition of salt to water raises its boiling point and lowers its melting point. Sketch the phase diagram for water containing salt, showing how it relates to the phase diagram for water (shown as dotted lines below).

Marks3

In terms of the relative entropies of all relevant species, explain why the boiling point of salt water is higher than that of pure water.

gas

B

solid

D

liquid

A

C

Pres

sure

(not

to sc

ale)

Temperature (not to scale)

THE REMAINDER OF THIS PAGE IS FOR ROUGH WORKING ONLY.

CHEM1102 2008-N-8 22/08(a)

• The following data were obtained for the reaction between gaseous nitric oxide and chlorine at –10 °C:

2NO(g) + Cl2(g) → 2NOCl(g)

Marks2

Experiment Number

Initial PNO (atm)

Initial (atm)

2ClP Initial Reaction Rate (atm s–1)

1 2.16 2.16 0.065

2 2.16 4.32 0.130

3 4.32 4.32 0.518

Derive an expression for the rate law for this reaction and calculate the value of the rate constant.

Rate law:

Rate constant:

THIS QUESTION CONTINUES ON THE NEXT PAGE

CHEM1102 2008-N-9 22/08(a)

The mechanism for this reaction has been postulated to be that below. 2NO(g) N2O2(g) fast N2O2(g) + Cl2 → 2NOCl(g) slow

Work out the rate law expected for this mechanism and hence show that it is consistent with the experimental rate law and the chemical equation.

Marks 4

The reaction is exothermic. Draw the potential energy vs reaction coordinate diagram for this mechanism, labelling all species that can be isolated.

CHEM1102 2008-N-10 22/08(a)

• The structure of the antihistamine, ZyrtecTM, is given below.

NN

Cl OOH

OAB

C

Marks5

What is the name of the functional group in Box A?

What is the name of the functional group in Box B?

What is the name of the functional group in Box C?

By drawing an arrow on the structure above, clearly indicate the stereocentre in the structure of Zyrtec.

Draw the product of the reaction when Zyrtec is treated with LiAlH4 followed by dilute acid.

CHEM1102 2008-N-11 22/08(a)

• Consider compound F shown below. Br

Assign the stereocentre in compound F as (R) or (S), explaining your reasoning.

Marks 8

Draw the enantiomer of compound F.

When compound F is reacted with hot KOH solution, a product (G) is formed that shows three peaks in the 1H NMR spectrum in the region 7-8 ppm and three peaks in the region 5-6 ppm. Draw the structure of this product.

When G is reacted with dilute sulfuric acid, a further product, H, is formed. H has a peak at 3300 cm–1 in its IR spectrum. Draw the structure of product H.

Is H formed as a single enantiomer, as a racemate, or is H achiral?

Assuming an SN2 mechanism, draw the product of the substitution reaction between F and (CH3)2NH, indicating stereochemistry where appropriate.

F

CHEM1102 2008-N-12 22/08(a)

• Consider the compound J below.

Marks5

What is the systematic name for compound J.

Draw a constitutional isomer of J.

Draw a configurational isomer of J.

Draw the structure of the product formed when compound J is reacted with hydrogen gas (H2) and a palladium on carbon (Pd/C) catalyst.

J

CHEM1102 2008-N-13 22/08(a)

• Complete the following mechanism by adding curly arrows to illustrate the bonding changes that take place.

Marks5

Cl

H ClCl Cl AlCl3

OCH3Br+

Br O

THE REMAINDER OF THIS PAGE IS FOR ROUGH WORKING ONLY.

CHEM1102 2008-N-14 22/08(a)

• An unknown compound K with the molecular formula C4H8O gives the following spectroscopic data.

1H NMR: 1.06 ppm, triplet, integration = 3H 2.13 ppm, singlet, integration = 3H 2.47 ppm, quartet, integration = 2H

IR spectroscopy: stretch at 1715 cm–1.

Use the information above to deduce the structure of compound K. Give reasoning for the structure chosen.

Marks5

CHEM1102 2008-N-15 22/08(a)

• Devise a synthesis of 1,2-dibromobutane from butanal. Provide any intermediate structures and reagents. (Hint: More than one step is required.)

Marks 5

HBr

O

Br

THE REMAINDER OF THIS PAGE IS FOR ROUGH WORKING ONLY.

22/08(b) November 2008

CHEM1102 - CHEMISTRY 1B

1

DATA SHEET Physical constants Avogadro constant, NA = 6.022 × 1023 mol–1

Faraday constant, F = 96485 C mol–1

Planck constant, h = 6.626 × 10–34 J s

Speed of light in vacuum, c = 2.998 × 108 m s–1

Rydberg constant, ER = 2.18 × 10–18 J

Boltzmann constant, kB = 1.381 × 10–23 J K–1

Permittivity of a vacuum, ε0 = 8.854 × 10–12 C2 J–1 m–1

Gas constant, R = 8.314 J K–1 mol–1

= 0.08206 L atm K–1 mol–1

Charge of electron, e = 1.602 × 10–19 C

Mass of electron, me = 9.1094 × 10–31 kg

Mass of proton, mp = 1.6726 × 10–27 kg

Mass of neutron, mn = 1.6749 × 10–27 kg

Properties of matter Volume of 1 mole of ideal gas at 1 atm and 25 °C = 24.5 L

Volume of 1 mole of ideal gas at 1 atm and 0 °C = 22.4 L

Density of water at 298 K = 0.997 g cm–3

Conversion factors 1 atm = 760 mmHg = 101.3 kPa 1 Ci = 3.70 × 1010 Bq

0 °C = 273 K 1 Hz = 1 s–1

1 L = 10–3 m3 1 tonne = 103 kg

1 Å = 10–10 m 1 W = 1 J s–1

1 eV = 1.602 × 10–19 J

Decimal fractions Decimal multiples Fraction Prefix Symbol Multiple Prefix Symbol

10–3 milli m 103 kilo k 10–6 micro µ 106 mega M 10–9 nano n 109 giga G 10–12 pico p 1012 tera T

22/08(b) November 2008

CHEM1102 - CHEMISTRY 1B

2

Standard Reduction Potentials, E° Reaction E° / V S2O8

2– + 2e– → 2SO42– +2.01

Co3+(aq) + e– → Co2+(aq) +1.82 Ce4+(aq) + e– → Ce3+(aq) +1.72 Au3+(aq) + 3e– → Au(s) +1.50 Cl2 + 2e– → 2Cl–(aq) +1.36 O2 + 4H+(aq) + 4e– → 2H2O +1.23 Br2 + 2e– → 2Br–(aq) +1.10 MnO2(s) + 4H+(aq) + e– → Mn3+ + 2H2O +0.96 Pd2+(aq) + 2e– → Pd(s) +0.92 Ag+(aq) + e– → Ag(s) +0.80 Fe3+(aq) + e– → Fe2+(aq) +0.77 Cu+(aq) + e– → Cu(s) +0.53 Cu2+(aq) + 2e– → Cu(s) +0.34 Sn4+(aq) + 2e– → Sn2+(aq) +0.15 2H+(aq) + 2e– → H2(g) 0 (by definition) Fe3+(aq) + 3e– → Fe(s) –0.04 Pb2+(aq) + 2e– → Pb(s) –0.13 Sn2+(aq) + 2e– → Sn(s) –0.14 Ni2+(aq) + 2e– → Ni(s) –0.24 Co2+(aq) + 2e– → Co(s) –0.28 Fe2+(aq) + 2e– → Fe(s) –0.44 Cr3+(aq) + 3e– → Cr(s) –0.74 Zn2+(aq) + 2e– → Zn(s) –0.76 2H2O + 2e– → H2(g) + 2OH–(aq) –0.83 Cr2+(aq) + 2e– → Cr(s) –0.89 Al3+(aq) + 3e– → Al(s) –1.68 Mg2+(aq) + 2e– → Mg(s) –2.36 Na+(aq) + e– → Na(s) –2.71 Ca2+(aq) + 2e– → Ca(s) –2.87 Li+(aq) + e– → Li(s) –3.04

22/08(b) November 2008

CHEM1102 - CHEMISTRY 1B

3

Useful formulas

Thermodynamics & Equilibrium

∆U = q + w = q – p∆V

∆universeS = ∆sysS – sys

sys

HT∆

∆G° = ∆H° – T∆S°

∆G = ∆G° + RT lnQ

∆G° = –RT lnK

Kp = Kc (RT)∆n

Electrochemistry

∆G° = –nFE°

Moles of e– = It/F

E = E° – (RT/nF) × 2.303 logQ

= E° – (RT/nF) × lnQ

E° = (RT/nF) × 2.303 logK

= (RT/nF) × lnK

E = E° – 0.0592n

logQ (at 25 °C)

Colligative properties

π = cRT

Psolution = Xsolvent × P°solvent

p = kc

∆Tf = Kfm

∆Tb = Kbm

Quantum Chemistry E = hν = hc/λ

λ = h/mv

4.5kBT = hc/λ

E = –Z2ER(1/n2)

∆x⋅∆(mv) ≥ h/4π

q = 4πr2 × 5.67 × 10–8 × T4

Acids and Bases pKw = pH + pOH = 14.00

pKw = pKa + pKb = 14.00

pH = pKa + log{[A–] / [HA]}

Gas Laws PV = nRT

(P + n2a/V2)(V – nb) = nRT

Radioactivity

t½ = ln2/λ

A = λN

ln(N0/Nt) = λt 14C age = 8033 ln(A0/At)

Kinetics t½ = ln2/k

k = Ae–Ea/RT

ln[A] = ln[A]o – kt

2 a

1 1 2

1 1ln = - ( )k Ek R T T

Miscellaneous

A = –log100

II

A = εcl

E = –A2

04e

rπεNA

Mathematics

If ax2 + bx + c = 0, then x = 2b b 4ac

2a− ± −

ln x = 2.303 log x

PERIODIC TABLE OF THE ELEMENTS

1

2

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

1 HYDROGEN

H 1.008

HELIUM

He 4.003

3 LITHIUM

Li 6.941

4 BERYLLIUM

Be 9.012

5 BORON

B 10.81

6 CARBON

C 12.01

7 NITROGEN

N 14.01

8 OXYGEN

O 16.00

9 FLUORINE

F 19.00

10 NEON

Ne 20.18

11 SODIUM Na

22.99

12 MAGNESIUM

Mg 24.31

3 1ALUMINIUM

Al 26.98

14 SILICON

Si 28.09

15 PHOSPHORUS

P 30.97

16 SULFUR

S 32.07

17 CHLORINE

Cl 35.45

18 ARGON

Ar 39.95

19 POTASSIUM

K 39.10

20 CALCIUM

Ca 40.08

21 SCANDIUM

Sc 44.96

22 TITANIUM

Ti 47.88

23 VANADIUM

V 50.94

24 CHROMIUM

Cr 52.00

25 MANGANESE

Mn 54.94

26 IRON

Fe 55.85

27 COBALT

Co 58.93

28 NICKEL

Ni 58.69

29 COPPER

Cu 63.55

30 ZINC

Zn 65.39

31 GALLIUM

Ga 69.72

32 GERMANIUM

Ge 72.59

33 ARSENIC

As 74.92

34 SELENIUM

Se 78.96

35 BROMINE

Br 79.90

36 KRYPTON

Kr 83.80

37 RUBIDIUM

Rb 85.47

38 STRONTIUM

Sr 87.62

39 YTTRIUM Y

88.91

40 ZIRCONIUM

Zr 91.22

41 NIOBIUM

Nb 92.91

42 MOLYBDENUM

Mo 95.94

43 TECHNETIUM

Tc [98.91]

44 RUTHENIUM

Ru 101.07

45 RHODIUM

Rh 102.91

46 PALLADIUM

Pd 106.4

47 SILVER

Ag 107.87

48 CADMIUM

Cd 112.40

49 INDIUM

In 114.82

50 TIN

Sn 118.69

51 ANTIMONY

Sb 121.75

52 TELLURIUM

Te 127.60

53 IODINE

I 126.90

54 XENON

Xe 131.30

55 CAESIUM

Cs 132.91

56 BARIUM

Ba 137.34

57-71 72 HAFNIUM

Hf 178.49

73 TANTALUM

Ta 180.95

74 TUNGSTEN

W 183.85

75 RHENIUM

Re 186.2

76 OSMIUM

Os 190.2

77 IRIDIUM

Ir 192.22

78 PLATINUM

Pt 195.09

79 GOLD

Au 196.97

80 MERCURY

Hg 200.59

81 THALLIUM

Tl 204.37

82 LEAD

Pb 207.2

83 BISMUTH

Bi 208.98

84 POLONIUM

Po [210.0]

85 ASTATINE

At [210.0]

86 RADON

Rn [222.0]

87 FRANCIUM

Fr [223.0]

88 RADIUM

Ra [226.0]

89-103 104RUTHERFORDIUM

Rf [261]

105 DUBNIUM

Db [262]

106 SEABORGIUM

Sg [266]

107 BOHRIUM

Bh [262]

108 HASSIUM

Hs [265]

109 MEITNERIUM

Mt [266]

110 DARMSTADTIUM

Ds [271]

111 ROENTGENIUM

Rg [272]

22/08(b)

CH

EM

1102 -CH

EM

ISTR

Y 1B

N

ovember 2008

LANTHANOIDS

57 LANTHANUM

La 138.91

58 CERIUM

Ce 140.12

59 PRASEODYMIUM

Pr 140.91

60 NEODYMIUM

Nd 144.24

61 PROMETHIUM

Pm [144.9]

62 SAMARIUM

Sm 150.4

63 EUROPIUM

Eu 151.96

64 GADOLINIUM

Gd 157.25

65 TERBIUM

Tb 158.93

66 DYSPROSIUM

Dy 162.50

67 HOLMIUM

Ho 164.93

68 ERBIUM

Er 167.26

69 THULIUM

Tm 168.93

70 YTTERBIUM

Yb 173.04

71 LUTETIUM

Lu 174.97

ACTINOIDS

89 ACTINIUM

Ac [227.0]

90 THORIUM

Th 232.04

91 PROTACTINIUM

Pa [231.0]

92 URANIUM

U 238.03

93 NEPTUNIUM

Np [237.0]

94 PLUTONIUM

Pu [239.1]

95 AMERICIUM

Am [243.1]

96 CURIUM

Cm [247.1]

97 BERKELLIUM

Bk [247.1]

98 CALIFORNIUM

Cf [252.1]

99 EINSTEINIUM

Es [252.1]

100 FERMIUM

Fm [257.1]

101 MENDELEVIUM

Md [256.1]

102 NOBELIUM

No [259.1]

103 LAWRENCIUM

Lr [260.1]